For greater convenience and portability many modern electrical appliances and consumer products may be operated to draw power from dry cells (commonly referred to as "batteries") of standard size and electrical performance. For convenience and economy various batteries have been developed which may be recharged for re-use. A number of chargers, operating off household current, have been developed to charge these rechargeable batteries. However, due to differences in chemistry, nonrechargeable batteries such as carbon-zinc or alkaline batteries may leak, discharge gases, or in some cases rupture, if subjected to a recharging current. Thus, for safety purposes, battery chargers must be provided with means for discriminating between batteries which may be safely recharged therein, and those which may not. Certain known chargers prevent battery charging accidents by providing the chargers with electrical circuits capable of distinguishing between batteries which should or should not be charged. Other known chargers provide the rechargeable batteries with non-standard structure such as specialized cathode or anode terminals which will only fit in and be charged by compatible battery chargers. Distinguishing electrical circuits within chargers are undesirable due to their added cost. Specialized anode or cathode structures require non-standard manufacturing capabilities and likewise add to battery cost.
What is needed is a charger which will recharge only compatible batteries and a compatible battery which may be manufactured at low cost.